The present invention relates to hydroelectric assemblies for hydroelectric plants, and more particularly, to a self-stabilized hydromotive assembly and, eventually, to a water storing dam adapted to receive it.
The aim of these hydromotive assemblies, positioned in coincidence with the open ends of the water flow circulations paths engineered through the main body of these dams; is to convert the inherent gravitational energy of the mass of water stored in the reservoirs defined behind said dams, into electric energy. The efficiency of this conversion is particularly imperative in horizontally arranged hydroelectric machines.
It is an aim of the present invention, to introduce the principle of the turbine-generator set arrangement concept engineered around a substantially horizontally positioned axis; or around a slightly slantingly positioned axis.
This arrangement, although having a plurality of technical advantages as it will be seen later; has not been popularized up today because of a plurality of deterring questions which are expected to be solved by means of the teachings introduced by the present invention.
One of these deterring questions concerns the up until today most popularized hydroelectric set engineered around the substantially positioned vertical axis concept, which imposes mechanical engineering principles upon hydraulic engineering ones.
It is known that in a hydroelectric station, the highest operational efficiency is attained when the engineered passages which directs the water flow through the dam, are shaped like rectilinear structural embodiments. If these passages have bends, scrolls, elbow draft diffusers, etc; the efficiency of the energy conversion is reduced because of the increased friction between the water flowing along them, and the inner surfaces thereof; thus reducing the amount of energy output of the hydroelectric station engineered on said dam.
Furthermore, the erection costs of these civil engineered structures having so complicated water passages, is very expensive and puts a great financial overburden on the respective enterprises. There are also, great constructive delay involvements on these engineered projects before putting them in the commissioned operative status.
Because of the introduction of the horizontal axis engineered concept, all these deterring factors are expected to be passed away.
Another aim of the present invention, concerns with the industrial modulated principles involved in the transportable self-stabilized hydroelectric assembly concept. By means of this principle, industrial engineered concepts are expected to be introduced in massive terms, into a technology up today mostly dominated by engineered craftsmanship principles.
This is so, because the best hydroelectric station engineered project must be designed under standardized concepts and erected with mass produced industrial components, thus saving erection time and financial costs.
Furthermore, under operational performance, the concerned hydroelectric station must not have shutdown delays for cause of maintenance procedures on generators and turbines.
It must have also, a very low investment figure realized in terms of money invested per kilowatt of electric power installed capacity.
Additionally, the erection time schedule required to install turbines and generators and put them in operation, must be the shortest possible one.
All these objectives are claimed to be made possible by means of the present invention.
All these considerations, which not only take into account hydroelectric station hydraulic efficiency and construction civil engineering techniques, but also financial requirements; have not been fulfilled up until today because the technology in horizontal axis engineered machines for hydroelectric generation had not been advanced enough in technical efficient terms in the last years, to keep pace with the most massive and spectacular nuclear electric generation development.
Consequently, less efficient design concepts and erection methods are used today, although they are very expensive and produce very large engineered structures, requiring great time delays to commission them.
Thus, it is an aim of the present invention to enable the provision of optimum erection methods by providing means for: manipulating, positioning, and mounting transportable hydroelectric equipment with relative ease and in a very short time interval, in spite of their cumbersome sizes and very heavy weights.
An additional aim of the present invention, has been to provide a novel engineering approach in technology design, whereby it is possible to increase the erection speed of a known hydroelectric project, thus minimizing the time delays to be supported until the commissioning date.
Because of their inherent efficiency and very modern technical features, and cost reduced manufactured bodies-components being individually lighter in weight by reasons of the advantages involved around the substantially horizontally engineered axis concept, expected to be massively introduced in the near future in hydroelectric equipments construction after the teachings of the present invention have been mastered; horizontal-axis hydroelectric sets having capsule mounted generators with Kaplan motive turbines or Deriaz motive turbines; and which today have been limited to very restricted practical applications on hydroelectric projects; will be progressively engineered to be installed in hydroelectric schemes having higher and higher hydraulic heads. In this way, the practical application field will be broadened, the actual engineered trends in hydroelectric construction will be flexibilized, and these useful types of machines will be progressively involved in this novel technique.
According to one aspect of the present invention, there is provided a transportable self-stabilized hydromotive assembly for an energy generation purpose, to be positioned against the structural body of a dam, and in functional coincidence with the water passing means embodied into the dam structure.
In the general arrangement, said hydromotive assembly has incorporated a water conduit in its structural body, defined by a lateral wall surrounding the motive turbine and having: a, generally shaped, annular first open end for water flow admission and a second open end for discharging the water entering the first open end, being circularly shaped in most cases.
Auxiliary means are available for purposes of water flow regulation, such as: movable vane distributors, movable bladed turbine runners, upstreamly positioned gates, downstreamly positioned gates, and the like; as is well known in the art.
This transportable hydromotive assembly also includes, defined in its structural body; a plurality of engineered buoyancy means of a volume at least sufficient to produce an upwardly lifting pull of a substantial numerical magnitude when said hydromotive assembly is positioned in submerged status for purposes of transportation procedures, or energy production.
These buoyancy means could be engineered as a plurality of watertight compartments, engineered around the generator's capsule and around the turbine conduit; which can be filled with fluid for sinking purposes or with gas for floatation purposes.
In this way, transportation procedures to the body of said dam or from the body of the dam, will be eased, and will be speeded. No heavy load strains will be introduced into the cranage facilities or other pulling means required to introduce these movable sequences into the body of said hydromotive assembly.
Furthermore, if a good distribution of these buoyancy means is engineered around the structural body of the hydromotive assembly; then, a good inherent stability will be introduced in the submerged status of said hydromotive assembly; and an additional second motivation of self static stability will be introduced, when said hydromotive assembly is moved for transportation procedures. As already said, these movable sequences are produced by means of: cranages facilities, movably sinkable and floatable pontoons, jacking arrangements, and the like; as is well known in the art.
The structural body of said transportable self-stabilized hydromotive assembly; incorporates also, a machine hall which includes all the necessary equipments for the full operational performance of said hydromotive assembly.
These means are listed as follows: turbine's governors, generator's controls, compressed air systems, lubrication systems, refrigeration systems, emergency energy sources, self propulsion for transportation procedures, incorporated switchyard and power transformation facilities, and the like.
In this way, a full operational and independent power packet will be available for purposes of being: manufactured at a plant, transported, and positioned at the dam site for purposes of electric power production.
This is the technical novelty involved around the concept explained in this invention entitled: Self-stabilized Hydromotive Assembly.
According to an even further aim of the present invention, a new concept in engineering design of hydroelectric stations, which flatly avoids the concreted structures of the machine hall and related powerhouse structures up until today incorporated at the body of the dam; is also provided.
Up until today, in the horizontal-axis disposition promoted by this invention; the capsule mounted generator of the bulb set has divided it into two sections: the mechanical section having the motive turbine, and the electrical section having the said generator.
Then, up until today, two access shafts were always necessary to be engineered in the machine hall and through the body of the dam if overall access to the machine during operation is required and specified.
Since the turbine runner and the electric generator are both horizontally connected by a shaft; then, these two bodies-components of the bulb set do not lie in the same vertical plane, as occurring in the vertical axis concept; thus making imperative the construction of said independent two shafts for erection purposes and access procedures.
This fact makes the machine hall engineered design in the horizontal axis engineered concept, more complicated that in the vertical axis concept; and led to the alternative design in which the generator is installed via the turbine runner shaft.
This simplification of the machine hall civil engineered structures, renders machinery installation and maintenance procedures, more complicated; particularly in large powered machines.
As a result, replacement of the generator components requires complete dismantling of the entire machine, giving very long outages.
With the introduction of our transportable self-stabilized hydromotive assembly concept, this deterring question is fully avoided because of the suppression of the expensive and difficult to build machine hall structure.
This basic technical fact provides a secondary and novel advantage which relates with maintenance procedures.
With the suppression of the machine hall concept; maintenance of motive turbines and generators is simplified too.
Machines which require important overhauls are instantly shifted away and replaced by operative ones arriving from the service center.
In this way, a unique service station is provided for the maintenance of a plurality of hydroelectric stations erected within a given watershed, thus revolutionizing maintenance concepts procedures followed up today in actual practices, provided by the present new technology.
According to an even further aim of the present invention, a horizontally positioned axis hydroelectric machine set is designed in such a way that the diametrical numerical magnitude of the generator's rotor, and the generator itself; is free to be engineered with a numerical magnitude substantially greater than the numerical diametrical magnitude of the turbine motive rotor. By means of this technical fact; an actually engineered connecting numerical parameter of only nearly: 1 to 1 (one to one); may be feasibly increased up to: 2 to 1 (two to one); in the generator's rotor/turbine's runner diametrical numerical comparison, made possible by this new proposed technology.
Because of this fact, the natural inertia of the generator's rotor measured in terms of: lb-ft.sup.2, of their moment of inertia; will be capable to be engineered with a multiplied factor of: 10 to 1 (ten to one), and more; in comparison with the moment of inertia provided with the old technology; in the old designs having restricted diametrical engineered rotors.
This basic engineered achievement is made possible because of the technical features provided by our horizontal axis concept disposition; in which, being the capsulated electrical generator not surrounded by concreted structures and related machine hall and powerhouse water intakes conduits; then, a free diametrical design is permitted at the external magnitude of said generator's capsule and also, at their respective contained generator's stator and generator's rotor; which are now free to be designed around diameters up until today only found in the vertical axis engineered disposition concept.
In this way, technical advantages up until today only found in said vertical axis technology, are now available to be applied to the horizontal axis technology expected to be fully promoted by this invention.
This question is very imperative because up until today; horizontal axis machines have suffered by limitations on their electrical engineered features. As already said, the generator is installed into the upstreamly water intake positioned hub capsule.
Since for hydraulic and economic reasons (because of said surrounding concreted structures), said bulb capsule must be made as small as possible; then, the electrical output must be produced by a generator having a rotor of very restricted diameter. This reduces the natural inertia of the machine, requiring very carefully designed turbine water conveying inlets and intakes to avoid unacceptable power fluctuations arising from an irregular incoming water flow pattern. For small machines connected at large electrical networks, said fluctuations may be allowable; but not in large powered hydroelectric stations or relatively small electrical networks.
Because of the technical features involved around our invented transportable self-stabilized hydromotive assembly concept, this deterring situation is avoided by means of a twofold technical procedure.
These twofold technical resources are established as follows: firstly, by increasing the diameter of the generator's rotor as previously established. Secondly, by decreasing the longitudinal path of the water flow circulation conduit which conveys actuating waters into the turbine runner propeller.
In our particular horizontal axis engineered disposition, said longitudinal path may be feasibly reduced from: 8..phi. . . . 6..phi.; actually found in the vertical and horizontal axis technologies; down to: 3..phi. . . . 2..phi., feasibles to be engineered in our new proposed technology; in which, .phi. represents the diametrical numerical parameter of the involved runner of the motive turbine.
Then, those twoway acquired technical advantages; provide a good stabilizing effect poured into the dynamic performance of our horizontal axis conceptual disposition. No more water flow fluctuations and water hammer hydraulic transient effects will be introduced into the incoming actuating masses of water which produce actuation upon the turbine runner, from one side.
From the other side, a good moment of inertia will be free to be engineered into the generator's rotor; thus adding a second motivation pointed to the objective of the intrinsic stabilization of the running machine.
Then, a machine having a twoway self-stabilization engineered design and conceptual development, will now be free to be manufactured to be installed for purposes of providing a very smooth performance in future hydroelectric developments; and also profitting of all the advantages which are feasible to be found in the horizontal axis conceptual disposition, to be engineered in the future in industrial massive terms.
This is the main objective expected to be reached by this invention entitled: Self-stabilized Hydromotive Assembly.
According to an even further aim of the present invention, a hydroelectric generator engineered concept is provided in which, the generator's rotor and generator's stator are both feasibly cooled without technical restrictions.
It is known that the output of a given hydroelectric machine rises accordingly to the square of the turbine runner diameter and with the 1.5 power of the hydraulic head. Due to the aforementioned restriction of the generator diameter, its length must be increased disproportionately with increasing turbine runner diameter and hydraulic head, making cooling more and more difficult.
While small capacity bulb turbine generators can be effectively air cooled, water cooling becomes necessary for very large units with outputs of more than: 60,000 kW. per machine.
With the closely-packed design disposition, this is difficult and expensive to accomplish.
Thus, up until today, all existing bulb turbine designs are limited to be engineered with turbine runners mostly having no more than 6.5 meters in diameter; and at hydraulic heads of no more than: 12 meters.
Heads in the range of: 30 meters and more; and individual power outputs in the range of: 100,000 kW. and more per machine, are technically impossible to be realized today.
However, with the teachings incorporated by the present invention, they are feasible to be engineered.
This technical fact is clearly understood when, we realize that in our horizontal axis particular conception; both, the generator's rotor and the generator's stator, having a great diametral numerical parameter; then, they are free to be engineered around the known technologies available today at the vertical axis disposition concept.
Then, the cooling of our horizontal axis generator will profit of the same technical resources available at the the cooling of actually engineered vertical axis generators having great individual outputs.
In this way, another deterring situation which up until today has restrained the development of the horizontal axis conceptual disposition, is again avoided.
According to an even further aim of the present invention, a hydroelectric generator horizontal axis concept is provided in which, mechanical bodies-components are all engineered around a solid structural arrangement.
Because of the above mentioned restrictions of the generator diameter, its length must be increased disproportionately with increasing turbine runner diameters and hydraulic head; and so the mechanical project spread along a very long axial structural arrangement. In this way, the force transmission path within a bulb turbine is very long.
For hydraulic reasons it is advantageous to arrange the runner of the turbine, with overhung bearings. Because of the horizontal position of the cantilever axis and the significant forces introduced by the own weight of the turbine runner, and the hydraulic forces induced into it by the actuating water flow, large bending moments are imposed on the bulb and thence via several long ribs through the water passages into the foundations at the body of the dam. The same fact, applies to the reaction moments from the generator stator which must be designed, in case of short circuit, to carry more than five times the loading in normal operation.
Once again, because of the teachings of the present invention all these deterring questions will be also eliminated.
This fact, is clearly seen, because in our horizontal-axis disposition; the connecting shaft between the turbine runner and the generator's rotor is very much shorter. Then, the bending moments are reduced and the overall arrangement is much more compact and solid in design and in mechanical endurance.
The mechanical efforts and stresses introduced into the concerned structural bodies-components, are very much reduced at a very much tolerable level.
This advantage is produced again, because of the more compact engineered design which belongs to the horizontal axis, transportable self stabilized hydromotive assembly design.
According to an even further aspect of the present invention, a method is provided for purposes of positioning a self-stabilized transportable hydromotive assembly against the respective open end of the inlet of the dam's water conveying means.
The method comprising the steps of: (a) Taking a self-stabilized hydromotive assembly having a structural body, a water conveying flow means inlet and a water flow means outlet, and a buoyancy engineered means defined in said structural body (b). Displacing the self-stabilized hydromotive assembly slightly upstream of said dam and so oriented that the longitudinal axis of said body, which coincides with the mechanical axis: is substantially parallel to the axis of said dam's water conveying means and positioned substantially thereabove (c). Displacing said self-stabilized hydromotive assembly in a substantially downwardly vertical sinking displacement (d). Directing the sinking self-stabilized hydromotive assembly until it faces the open end inlet of the dam conveying means (e). Displacing the hydromotive assembly to position its water outlet coincidently against the inlet of said dam's water directing means (f). Securing the self-stabilized transportable hydromotive assembly in such working position.
Although references in the specifications are detailed for horizontally positioned turbine-generators sets; it will be obvious that the teachings of the present invention are independent of the specific position of said axis; and that any other specific arrangement is feasible to be considered.